The Transforming Growth Factor-Beta (xe2x80x9cTGF-xcex2xe2x80x9d) superfamily represents a large number of evolutionarily conserved morphogenic proteins with diverse activities in growth, differentiation, tissue morphogenesis and repair. This superfamily includes osteogenic proteins (xe2x80x9cOPsxe2x80x9d) and bone morphogenic proteins (xe2x80x9cBMPsxe2x80x9d). OPs and BMPs share a highly conserved, bioactive cysteine-rich domain near their C-termini and have a propensity to form homo- and hetero-dimers.
Many morphogenic proteins belonging to the BMP family have been described. Some were isolated using purification techniques on the basis of osteogenic activity. Others were identified and cloned by virtue of DNA sequence homologies within conserved regions that are common to the BMP family. These homologs are referred to as consecutively numbered BMPs whether or not they have demonstrable osteogenic activity. While several of the earliest members of the BMP family were identified by virtue of their ability to induce new cartilage and bone, a number of other BMPs have different or additional tissue-inductive capabilities. For example, BMP-12 and BMP-13 (identified by DNA sequence homology) reportedly induce tendon/ligament-like tissue formation in vivo (WO 95/16035). Several BMPs, including some of those originally isolated on the basis of their osteogenic activity, can induce neuron proliferation and promote axon regeneration (WO 95/05846; Liem et al., Cell, 82, pp. 969-79 (1995)). Thus, it appears that BMPs may have a variety of potential tissue-inductive capabilities whose final expression depends on a complex set of developmental and environmental cues.
Many of the mammalian BMPs have been recombinantly expressed as active homo- or heterodimers in a variety of host systems, making therapeutic treatments using morphogenic proteins feasible. Implantable osteogenic devices comprising mammalian osteogenic protein for promoting bone healing and regeneration have been described (see, e.g., Oppermann et al., U.S. Pat. No. 5,354,557). Some osteogenic devices contain porous, biocompatible matrices that allow the diffusion of osteogenic proteins into the implantation site as well as the influx and efflux of progenitor cells. Osteogenic protein-coated prosthetic devices that enhance the bond strength between the prosthesis and existing bone have also been described (Rueger et al., U.S. Pat. No. 5,344,654).
This invention is based on the discovery that the tissue-inductive activity of a morphogenic protein can be enhanced by a hormone in the presence of a soluble receptor of the hormone.
Accordingly, this invention features a method for improving the tissue inductive capability of a morphogenic protein at a target locus in a mammal. In this method, the morphogenic protein and a first effective amount of a hormone and a second effective amount of a soluble receptor of the hormone are administered to the target locus, wherein the morphogenic protein is capable of inducing tissue formation when accessible to a progenitor cell in the mammal, and the hormone and the receptor in combination enhance that capability. The morphogenic protein, hormone and hormone receptor can be administered simultaneously to the target locus. Alternatively, the three components are administered separately, in any order: for instance, the morphogenic protein can be administered first, and then the hormone and hormone receptor are administered together; or the morphogenic protein and the hormone are administered together first, and then the hormone receptor is administered. In one embodiment, the morphogenic protein is administered via a nucleic acid (e.g., a plasmid, a viral vector, or naked DNA) that comprises a sequence encoding the morphogenic protein and is capable of expressing the morphogenic protein in the appropriate progenitor cells of a patient.
The morphogenic protein may comprise a pair of subunits disulfide-bonded to produce a dimeric species, wherein at least one of the subunits comprises a polypeptide belonging to the BMP protein family. For instance, the morphogenic protein may comprise an amino acid sequence sufficiently duplicative of the amino acid sequence of a reference BMP such as BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7 (OP-1), BMP-8, BMP-9, BMP-10, BMP-11, BMP-12, BMP-13, COP-5, or COP-7, such that it has morphogenic activity similar to that of the reference BMP. In one preferred embodiment, the morphogenic protein is a homo- or heterodimer comprising a BMP-2 or BMP-7 (OP-1) subunit.
The morphogenic protein is capable of inducing tissue formation. For instance, it may be capable of inducing the progenitor cell to form tissue tendon/ligament-like or neural-like tissue; or it may be an osteogenic protein that is capable of inducing the progenitor cell to form endochondral or intramembranous bone, or cartilage. The method of this invention thus can be used to induce tissue regeneration or repair in a variety of tissue defects such as bone, cartilage, soft tissue and neural tissue defects.
Hormones useful in this invention include but are not limited to cytokines (e.g., interleukins 1 through 18), growth factors (e.g., fibroblast growth factor, vascular endothelial growth factor, platelet-derived growth factor, TGF-xcex2, or prostaglandin) or morphogenic proteins.
The invention also features pharmaceutical compositions and kits comprising a hormone and a soluble receptor thereof for improving the tissue inductive activity of a morphogenic protein. This invention also provides implantable morphogenic devices for inducing tissue formation in allogeneic and xenogeneic implants. Such devices comprise a morphogenic protein, a hormone and a soluble receptor thereof disposed within a carrier. Methods for inducing local tissue formation from a progenitor cell in a mammal using those compositions and devices are also provided. A method for accelerating allograft repair in a mammal using those morphogenic devices is provided. This invention also provides a prosthetic device comprising a prosthesis coated with a morphogenic protein, a hormone and a soluble receptor thereof, and a method for promoting in vivo integration of an implantable prosthetic device to enhance the bond strength between the prosthesis and the existing target tissue at the joining site. Methods for treating tissue degenerative conditions in a mammal using the pharmaceutical compositions are also provided.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Exemplary methods and materials are described below, although methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention. All publications and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. The materials, methods, and examples are illustrative only and not intended to be limiting.